Micrometer attachment for engineerss transits



om 9 w .L c o d e t n e t mm m W- 6 0 N MICROMETER ATTACHMENT FOR ENGINEERS" TBANSITS.

. (Application filed Jan. 31, 1898.) (No Model.)

2 Sheets-Sheet L THE mums PUERs morouma. wAsumuT Pat'entad Oct. ll, I898. G. W. DICKINSON.

MICRUMETEB ATTAGHMENT FOR ENGINEERS TRANS|TS.-

(Application filed Jan. 31, 1898.)

2 Sheets-Sheet 2.

(No Model.)

UNITED STATES PATENT OFFICE.

GEORGE WV. DICKINSON, OF'SHELBYVILLE, ILLINOIS.

MICROMETER ATTACHMENT FOR ENGINEERS TRANSITS.

SPECIFICATION forming part of Letters Patent No. 612,314, dated October 11,1898. Application filed January 31, 1898. Serial No. 668,632. (N model.)

To all whom, it may concern:

Be it known that I, GEORGE W. DICKIN- SON, of the city of Shelbyville, Shelbycounty, State of Illinois, have invented certain new and useful Improvements in Micrometer Attachments for Engineers Transits, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

Myinvention relates to micrometer attachments for transits, said attachments providing means for the reading of angles to minutes and seconds after the degrees and halfdegrees have been found on the graduated circle of the transit.

Myinvention consists of the novel construction, combination, and arrangement of parts hereinafter shown, described, and claimed.

Figure 1 is a plan view of an instrument to which my invention is applied. In this view the telescope and various other parts of the instrument are not shown; Fig. 2 is a view of the under side of the instrument shown in Fig. 1. Fig. 3 is an enlarged transverse sectional view taken approximately on the line 3 3 of Fig. 1. Fig. 4 is a vertical sectional view taken approximately on the line 4 4 of Fig. 3. Fig. 5 is a front elevation of the dialplates made use of in carrying out myinvention, which view is taken as looking in the direction indicated by the arrow A, Fig. 1.

Referring by numerals to the accompanying drawings, 1 indicates a compound spindle, comprising the outer sleeve 2,which is attached to the tripod-head and leveling-plate, and a tapered sleeve 3*, which is rigidly fixed to the under side of the center of the lower plate 3. Formed in the periphery of this plate 3 is a continuous groove 4,which is provided with suitable cogs or threads 5, which are adapted to be engaged by a .worm,' yet to be described. Arranged for rotation inside the sleeve 3 and forming a part of the compound spindle 1 is a tapering spindle 6, that is rigidly carried by the Vernier plate 6. Formed integral with the edge of this plate 6 is a downwardly-projecting flange 7, that incloses the worm-rack 5, and formed in this flange 7 is an aperture 10, the purpose of which will be presently described.

11 indicates an arm the inner end of which is provided with the ring 12, that is rotatably mounted upon the flange 12, which incloses the upperend of the sleeve 2,and which flange is fixed to the under side of the plate 3. A set-collar 13 is fixed by means of a set-screw upon the lower end of this flange 12 and holds the ring 12 in proper position upon said flange 12.

16 indicates a bracket, with the under side of which is formed a lug 17, through which lug passes the thumb-screw 18, said thumbscrew passing into the screw-threaded recess 15 and providing means for rigidly holding the bracket 16 to the arm 11. One end of the bracket 16 is extended upwardly to form the double cone-bearing 19, and the opposite end of the bracket 16 is provided with the integr'al upwardly-extending disk 20, through which passes the sleeve 21, provided with the flange 21. This sleeve forms a bearing 22, which is in horizontal alinement with the bearing 19. Fixed in any suitable manner to the inner face of the bracket 16 immediately adjacent the vertical disk 20 is a leafspring 23, the free outer end of which engages against the lug 24, formed integral with one side of the arm 11. The normal tendency of this leaf-spring 23 is to throw the bracket 16 away from the head 14 of the arm 11. Formed integral with the rear edge of the vertical disk 20 is a pair of vertically-arranged oppositelyprojecting lugs 25, and rigidly fixed to the flange 7, immediately behind these lugs 25, is a plate 26, from the top and bottom edges of which project arms 27, through the outwardlyturned ends of which pass screws 28, the ends of which are pointed and engage in the ends of the lugs 25. In this manner the bracket 16 is connected by a vertical hinge to the flange 70f the upper plate 6, and said bracket is adj ustably carried upon the end of the arm 11. As the adjustment between this bracket 16 and the arm 11 is very limited, the aperture through the lug 17 may be but a fraction larger than the body of the set-screw 18 in order to give the proper play between the parts while said bracket is being adjusted.

Arranged for rotation in the bearings 19 and22jis a shaft 29, upon the end of which, outside the circular flange 21, is formed a disk 30, that is provided with an inclined or beveled edge 31, the face of which beveled edge is provided with the graduated scale.

This is the minute and second disk. Formed integral with the outer face of the disk 30 is the milled head 31, which is engaged by the thumb and finger when the disk 30 and shaft 29 are rotated.

32 indicatesa disk having a milled edge, and said disk is rotatably arranged upon the flange 21. Formed on the periphery of this second disk 32 is a Vernier 33, which is used in connection with the graduations on the disk 30.

Securely fixed to the top of the disk 20 is a plate 34, which carriesthe Vertical finger 35, the pointer 36 of which extends over the periphery of the second disk 32 and downwardly a short distance on the inclined face 33. This pointer is in direct vertical alinement with the axis of the shaft 29.

Rigidly located upon the shaft 29 is a worm 37, which is of such a diameter as that it will pass through the aperture 10, formed in the flange 7, and engage in the threaded rack 5.

Before describing the operation of my improved device it may be stated that in this application the attachment is shown in connection with a transit and that as the wormthread is a half-degree thread necessarily one complete revolution of the shaft 29 will turn the plate 6 one-half a degree.

In taking a bearing the plates 3 and 6 are moved relative to each other, so that the zeropoint on the vernier on the upper plate 6 coincides with the zero of the upper graduated circle of the transit. The telescope is directed to the first object, after which the thumb-screw 18 is loosened, and by so doing the leaf spring 23 throws the bracket 16 away from the head 14, and this movement disconnects the worm 37 from the rack 5. The plates 3 and 6 are now free to operate independently of each other, and the telescope is brought to bear as near as possible upon the second object by manually engaging said telescope. This movement may give the exact degree and part thereof desired; but where the exact point desired is a fraction of a degree more or less than the degree shown on the transit-Vernier or where it is desired to bring the telescope into exact alinement with the second object the thumb-screw 18 is tightened, which brings the bracket 16 against the head 14 and the worm 37 into engagement with the threaded rack 5. The operator now rotates the shaft 29 by turning the milled head 31 in the proper direction, and this movement necessarily causes the worm 37 to engage with the threaded rack 5, and the plate 6 is moved a corresponding distance relative to the plate 3, and thus the shaft 29 performs the function of a tangentscrew and brings the telescope directly upon the second object. Necessarily with the turning of the shaft 29 the disk 30, having the graduated edge, is partially rotated and the operator can readily note the minute and second upon the graduated edge thereof after the operation is completed.

Should it be desired to repeat a number of small angles, the disk 32 on which the Vernier 33 is located is brought into use. After the first angle has been ascertained in the manner heretofore described and it is desired to repeat the angle the disk 32 is rotated upon the flange 21 independently of the disk 30 until the zero-point of the Vernier coincides with the zero-point of the graduations on the disk 30. This forms a starting-point for the succeeding angle, and said operation can be repeated the desired number of times.

Thus it will be seen how I have provided a very simple and efficient attachment. for a transit which when operated will readily indicate the exact minute and second of angles, and which attachment comprises simple and eflicient means for readily repeating any number of small angles.

I claim- 1. A micrometer attachment for transits, constructed with an arm swung from the center of the fixed plate of the transit, in the periphery of which fixed plate is formed a continuous row of worm-teeth, a transverse bar held to the end of the arm and movable lengthwise thereof, a shaft journaled in the upturned ends of said bar, a worm carried by said shaft for engaging the worm-rack, an indicating-disk carried by the outer end of said shaft and a second disk rotatably mounted in front of the first-mentioned disk and operating independently thereof, substantially as specified.

2. A micrometer attachment for engineers transits, constructed with a fixed plate, in the periphery of which is formed a series of wormteeth, a plate rotatably mounted uponsaid fixed plate, an arm swinging from the center of the fixed plate, a bracket carried by the outer end of said arm and movable lengthwise thereof, bearings formed integral with the ends of said bracket, a shaft rotatably mounted in said bearings, a worm carried by said shaft which engages the worm-teeth in the periphery of the fixed plate, a circular lug formed integral with the outer face of one of the bearings, a disk rotatably mounted upon said lug, a disk formed integral with one end of the shaft adjacent the first-mentioned disk, a bracket carried by the rotating plate, and hinge connections between said bracket and the end of the first-mentioned arm, substantially as specified.

In testimony whereof I affix my signature in presence of two witnesses.

GEORGE W. DICKINSON.

Witnesses:

ALBERT J. MOOAULEY, M. P. SMITH. 

